Temperature and Watering Regime Interactions in Shaping Canola Reproductive Yield and Seed Quality

Crops are continually subjected to frequent and extreme changes in climate, such as high temperatures and soil water deficits. Many studies have shown the individual effects of these factors on plants, but their combined effects on reproductive growth and subsequent seed germinability have received little attention. In this study, we used canola (Brassica napus) plants and grew them through their lifecycle under two temperature regimes (20/10 °C and 24/14 °C, 16 h light/8 h dark) in controlled-environment growth chambers. Half of the plants were watered to field capacity (well-watered) and the other half at wilting point (water-stressed). During the reproductive stage, the flower, silique, and seed traits were measured. Higher temperatures decreased the petal width by 1.17 times but increased petal anthocyanins by 1.03 times. The water deficit decreased the silique length and total seed number by 1.21 and 1.32 times, respectively, but increased nectar sugar concentration by 1.28 times. The total volume of nectar was affected by the interaction of temperature and water. The nectar volume was lowest in the water-stressed plants under higher temperatures (2.66 ± 0.29 µL per flower) but highest in the well-watered plants under the same temperature regime (5.73 ± 0.37 µL per flower). In conclusion, the combined effects of temperature and water were less pronounced than the individual effects of these factors on canola reproductive yield.